I think it's about high time I write up a FAQ for properly diagnosing and repairing cylinder misfires. For you noobs, I have two threads devoted to reuilding my 318, and I've seen everything you are encountering, and then some.

 

Yep, thats me, noob!

Im also cursed with being curious, so I cant bring myself (or my wallet) to a mechanic, especially once I start.

Im off to the garage now, I will report back.

Looking forward to the misfire guide.

Thanks!

 

Ok, so I pulled the #8 plug, I can see why theres a misfire on that cylinder.

Anybody able to explain why this would have happened, these plugs are no more than4 months old?




[IMG]local://upfiles/67976/38AB7B73987F4105BD6BDCE0D932EFBB.jpg[/IMG]

 

Pre-Ignition
[hr]
A melted or burned center and/or ground electrode, blistered insulator and aluminum or other metallic deposits on the insulator

Symptoms:[*]Loss of power causing engine damage[*]Pre-ignition occurs when combustion begins before the timed spark occurs.

Causes:[*]Plug insufficiently tightened[*]Engine insufficiently cooled[*]Ignition timing too advanced[*]Plug heat range too hot

Found this, for the record the plug was tight
Engine never overheated that I know of (I drive it 99 percent of the time)
I made no adjustments involving timing.
Plugs were the ones recommended by NAPA.

I did do the TPS mod, and it WAS set at .65 orginally then.71, I just dialed it into .75

Any other ideas on causes?

 

That's ugly.
Are those the stock spec plugs? Did you replace them yourself?
That looks like a severely overheated plug and possible signs of pre ignition or detonation. I think that injector might be plugged or a possible vacuum leak on that cylinder. Better get that fixed ASAP! I would do a compression test and see if there is any valve or ring damage.

 

Got any links to these threads?

 

Yes I did replace them myself, just called NAPA and told them what I had and they gave me the plugs.

They are Autolite Platium AP5224, RockAuto does list them as stock plugs.

 

The Final Chapter is in my sigline. Do some searching and you'll find one of them. I can PM it to you if you're interested.

arcsum68
Don't run Platinums in the 318.

 

A bad plenumgasket is considered a LARGE vac leak. The plugged cat could have started that spark plug problemand a damaged electrode continued to add to it.

I'd go ahead and check the fuel rail and injectors as well, heck clean em all while your in there, it'll only help to run it better. You'll need a 3/8" fuel line disconnect tool, that's the only thing special I can think of to do it.It's relatively easy. Just pull the fuel relay in the PDC and start up the truck to relieve the pressure on the rail.Disconnect the battery, pulloff the air hat, disconnect the fuel line and injector plugs, unbolt the fuel rail andand wiggle it straight up and out. I think that's about it, been a while since I did it.

Fix the plenum soon, then run a cooler spark plug (autolite 3923 coppers) and top it off with a 180* t-stat to run the coolant cooler through the cylinder heads and pull the heat down. Also check the TSB on spark plug wire routing as misfires can happen due to thinner wires running too close to each other and arcing. I'm pretty sure the #4 and #8 wires need to be kept away from each other.

That's a BAD plug pick, You really do need to run a compression test to see ifyou've got a badring or burnt valve in there.

 

Will do, gonna head over and get some parts here in a few.

Will I need to run the compression test on all the cylinders?

Thanks for all the information, will post back asap.